As a tire wears, its circumferential tread decreases in radial thickness. In addition, tread elements such as grooves, ribs, and sipes decrease in radial thickness. For example, a series of lateral grooves may be in communication with a first shoulder and a second shoulder when the tire is new, but not be in communication with the first and second shoulders when the tire is worn because at least one of the lateral grooves has a depth less than the depths of the remaining lateral grooves.